The Short-Term Results of Contrast Enhanced MR Angiography and MR Imaging in the Early Period after Renal Transplantation

Abstract

Purpose: Our objective was to evaluate the usefulness of three-dimensional contrast enhanced MR angiography (3D CE MRA) for assessment of renal parenchyma itself, arterial inflow stenosis, and peritransplant fluid collection in the early period after renal transplantation. Methods: Between January 2010 and April 2011, a consecutive series of 144 renal transplants was examined with 3D CE MRA 14 days after transplantation. MR angiography studies were analyzed for the volume of renal parenchyma, presence of arterial stenosis, renal infarction, and peritransplant fluid collection. The degree of renal transplant artery inflow stenosis was graded qualitatively as < 50% = mild, 50-70% = moderate, >70% = severe. Results: Ninety-two (63.9%) of the 144 patients had normal CE MRA which were no parenchyma infarction, no fluid collection and no arterial inflow stenosis. MR angiography showed parenchyma infarction (n=17, 11.8%), arterial inflow stenosis (n=23, 16%), lymphocele (n=14, 9.7%) and hematoma (n=6, 4.2%). Among the patients with arterial inflow stenosis, 10(6.9%) showed mild, 5 patients (3.5%) moderate, and 8 patients (5.6%) severe stenosis. Six patients of severe arterial stenosis on CE MRA underwent selective digital subtraction angiography (DSA). One patient with suspicion of severe arterial stenosis on MRA had moderate narrowing on DSA. The mean creatinine level at 1month, 6month and 1 year after transplantation were not significantly different in patients with severe arterial stenosis from those of others (P = 0.728, 0.694, 0.480). The prevalence of graft loss (n=2) was high in patients with severe arterial stenosis (P = 0.025) but AR episode was not different (P = 0.307). Conclusion: The incidence of renal parenchyma infarction, peritransplant fluid collection and arterial flow stenosis is unexpectedly high in the early period after kidney transplantation. MR angiography and MR imaging allows rapid global assessment of renal parenchyma, renal transplant arterial system, and peritransplant fluid collection. It can also help detect or exclude many of the various causes of renal transplant dysfunction.